Pressure-controlled regulating means for furnaces



Dec. 1 1925- c. 1.. HOWSE PRESSURE CONTROLLED REGULATING MEANS- FORFURNACES Filed March 2', 1922 WATER fKlSSl/AE i 72 07* 606776 SI. fowaeq ,55/ MMMMM% Patented Dec. 1, 1925. I

UNITED STATES PATENT oer-mg,-

cunrrs L. nowsn, on Burton, MICHIGAN, ASSIGNOR T0 01mm nmrnnnnoumroncournw, A conroim'rron or DELAWARE.

PRESSURE-CONTROLLED REGULATING MEANS I03 FURNACES.

Application filed March 2, 1922. Serial No. 540,651.

To all whom it may concern:

Be it known that I, CURTIS L. Howsn, a citizen of Great Britain,residing at Detroit, in the county of Wayne and State of Michigan, haveinvented certain new and useful Improvements in Pressure-ControlledRegulating Means for Furnaces, of which the following is aspecification.

In the operation of steam-boiler furnaces, it is desirable automaticallyto control the conditions which affect combustion-rate so that, asboiler pressure rises above a desired quantit combustion may bedecreased, and

whent e boiler pressure falls, the furnace may be conditioned forincreased combustion. Two of the regulable conditions affecting aforced-draft furnace are air supply rate and stack-damper adjustment,and 1n many installations it is highly desirable to vary theseconditions coincidently to tend to malntain substantially uniformpressure conditions in the combustion space of the furnace.

One of the objects of my invention is to provide a novel and efiicientcontrol system for furnace regulation, accordantly with pressureconditions in the boiler. A further object of my invention is to providenovel and efficient mechanism for control, which will be simple andrugged in construction, adaptable to installations widely varying indetail requirements, and effecting all control operations in a manner atonce sensitive, forceful and smooth. Other and further objects of myinvention will become apparent from the following description, taken inconjunction with the accompanying drawing, wherein I have illustrated asingle embodiment of my invention for purposes of disclosure, in asystem of boiler-furnace regulation. I

In the drawings Fig. 1 is a diagrammatic side elevation with partsbroken away showing the application of m invention to control of anunderfeed-sto er furnace equipment; Fig. 2 is an enlarged view withparts broken away showing control mechanisms detached; Fi 3 is a reducedplan view of the construction shown in Fig. 2.

The boiler 10 is shown as served by a furnace having stack 11 equippedwith damper 12 to e regulated, and where, as shown, an underfeed stoker13, or other grate structure requiring forced draft is employed, the airsupply may be afforded such arm 17 may have a sector 19 to which isconnected the chain 20 constituting part of a connection to acontrol-engine 21, the construction and operation of which adapts it forcontrolling actuation of either or both the rheostat and thestack-damper. The rheostat chain 20 is connected to the verticalextension 22 of piston rod 23, and to such extension is also connectedthe damperpositionmg means, shown as gear 24 on the damper shaftoperated by sector rack 25 of a pivoted lever 26 slotted for variableleverage connection with a link 27 which is pivotally connected to thepart 22 or a lug thereon. When piston rod 23 draws down the connection22, it moves the rheostat arm to cut resistance into the motor circuit28, to slow the motor 15, and rotates the stack dam er in closingdirection.

The regulatlng engine shown comprises a hydraulic cylinder 30 into whichliquid may be introduced or from which it may be permitted to escapenear one end to act on piston 31, the other end of the cylinder havingonly a drain connection to a drain pipe 32 liquid-introduction andeductionbeing controlled by a valve structure 33 which is under jointcontrol of a pressure responsive device 34 (connected with the boiler)and of the piston itself.

In the simple and effective form of valve mechanism shown, a single portin the upper end of the cylinder, as shown at 36, serves both for liquidsupply and eduction, such port communicating with a valve-cylinder 37 inwhich slides the double-headed valve 38. The water supply pipe 39,maintained under a constant water-pressure, opens to the valve-clearancebetween the heads, so that when the valve is depressed below the normalposition shown it opens communication between the supply pipe 39 and theport 36. In normal position, as shown, the

valve opens connection between port 36 and a relief port 40 connectedwith the drain pipe 32. An open channel ,43 may connect this relief areawith the space above the upper valve head, so balancing the valve.

The pressure-responsive device 34 and the piston 31 are so, connectedwith the valve. for joint control thereof, that response of saidpressure-responsive device to increase pressure acts to move the valvedownward toward in-flow position for admission of more liquid to thecylinder, whereas downward movement of the piston, resulting from suchfluid in-fiow, tends to raise the valve toward out-flow or reliefposition. With such an organization for coaction be tween the valve, thepressure-responsive device, and the piston, it follows that opening ofthe valve due to action of the pressure responsive device will result inpiston-movement which will act upon the valve to neutralize the valve,moving it in a direction opposite to that in which it is moved by thepressure-responsive device. Specific mechanical organization, for thisjoint, and cooperative, action may take various forms, and as to detailsof valve structure, pressure-responsive actuating mechanism andmechanism to be actuated by piston movement, many changes may be wroughtfrom the specific construction which I illustratively show.

For operating the single one-piece valve preferably used, lever 45 haspivotal connection 46 to the valve stem and pivotal connections 47 and48 respectively to the piston-controlled part and to thepressure-responsive part. Pivot 48 receives link 49 adjustable in lengthas by the turn-buckle 50 and connected at its lower end to the movableelement of the pressure-responsive device 34. Such pressure-responsivedevice may be of bellows-diaphragm type or other character forexpansion, but is shown as a gang of parallel Bourdon tubes 51 having atone end a common steam connection 52 to the boiler and at the other enda common closing union 53 to which the lower end of link 49 is pivoted.A weight 67 on lever 45 is movable to variably load the device.

Pivot 47 receives the upper end of a link,

- 55, the lower end of which is vertically movable by the piston 31,This link engages crank pin 56 positioned in one of the holes 57 locatedat difi'erent radial distances from the center of a .rockin head 58which is mounted in the bracke 59 and which has a non-circularshaft-portion 60 connectible with a lever 61 so as to bring any one oftheholes 57 to appropriate working osition. This lever 61 has itsslotted en 62 engaged by a pin on the vertical rod 63 carried by rod 22,movable with piston 31.

Where an electric motor is controlled in the manner hereinbefore stated,it is deances, as follows,

sirable that means be provided whereby rupture of the motor circuit maybe made to throw the rheostat to full-resistance condivalve member 38releasable from the controlling lever system, and independentlyactuatable, upon rupture of the clrcuit 28, Thus, as shown, lever 45 maycarry an electro-magnet 65 connected in the circuit 28, its armature 66carrying the pivot 46 for the valve stem and being normally frozen orfully attracted so as normally to rigidify the connection of the lever45 with said valve. Thus, as long as the magnet is energized, the leverelement acts as though directly connected with the valve stem, butshould the motor circuit break and the magnet become de-energized, itreleases its armature 66 which falls, depressing the valve regardless ofthe position or operation of the lever 45.

The operation of the regulating appliwill now apparent: Under normaloperating conditions assume the boiler to be met up to normal pressureand the regulating appliances to be positioned as illustrated in Fig. 2.Demand on the boiler causes a drop in pressure which should be met by anincrease of air supply from fan 14 and a commensurate opemng of damper12 in the stack. 1 The pressure drop is communicated by pipe 52 to theBourdon spring pressure-responsive device 51, so that the springscontract, drawing down link 49 which rocks lever 45 on pivot 47. Themagnetic connections 65, 66 being rigidified under normal conditions,valve member 38 is raised, opening the port 36 to the relief port 40 andoutlet pi 32. The liquid normally filling the cyhndis r 30 above piston31 therefore flows out of the cylinder, pending closure of the valve,since weight 18 on the rheostat arm 17 constantly tends to raise thepiston. As the piston rises so does the slotted end of lever 61, and thecrank pin 56 draws down the link 55, lowering ulcrum 47 so that lever45, now fulcruming on pivotal connection 48, has its valvecarrying enddepressed, and this action continues until valve 38 closes. Thus thepiston comes to rest in a vertical position consistent with the positiontaken by the ressure-responsive device in its contractlon due topressure-reduction. The stated piston movement is communicated to boththe rheostat arm and the-damper, the movable rheostat contact movingclockwise to cut out resistance, speeding up the motor 15 and thereforethe blast fan 14, and the damper 12 being moved toward open position.When, now, boiler ressure rises, the pressure-responsive dance 34expands, elevating link 49 and rocking lever 45 on point 47 as afulcrum, so depressing the valve 38. This opens communication betweenthe water suptlon and to this end I preferably make the ply pipe 39 andthe cylinder port 36, so that water under adequate pressure flows intothe cylinder, forcing down the piston 31, with the result that, throughthe piston-controlled leverage system, link 55 is forced upward, rockinglever on 48 as a fulcrum until valve 37 is raised to its neutralposition shown, cutting off the water supply to port 36. This operationis, of course, converted into a resistance-increasing actuation of themotor-rheostat and a damper-closing operation. Magnet 65 serves only asa protective device in connection with the motor, and in the eventof'rupture of the motor circuit the resultant de-energization of themagnet frees its armature 66 to drop, regardless of the position oflever 45, driving own the valve 38 to open communication between liquidsupply pipe 39 and the cylinder, so that piston 31 is forced downthrough its full range of movement, turning the rehostat tofull-resistance position and closing the damper. Of course wherefanspeed control is effected through some actuating device other than anelectric motor, electro-magnetic connection may be eliminated, and whereinstallation is made in a natural draft furnace merely to govern thedamper adjustment, the rheostat connections ma be omitted and thecounterbalancing weight 18 transferred to the sector-carrying portionsof the damper lever 26. Of course I do not limit myself to thevariations specifically suggested, as many changes may be made withinthe spirit of my invention and the scope of the appended claims.

I claim:

1. The combination with a steamboiler, a forced-draft furnace thereforhaving a draft-fan, an electric motor for driving said fan andspeed-changing means for said motor, of a pressure-controlled engine foroperating sa1d speed-changing means com rising a cylinder, a pistontherein loade to tend to move toward one end of said cylinder andoperatively connected with said speed-changing means to'actuate thelatter,-

said valve for moving the same in either direction, sa1d connectionsincluding a normally energized electro-magnetic device having a partarranged, when de-energized, to move said valve to one extreme ofposition, operative connections between said piston and saidvalve-moving connections whereby iston-movement tends to restore saidvalving means to normal position, and electrical connections betweensaid electro-responsive device and the motor circuit whereby rupture ofthe latter may de-energize the former.

2. The combination with a steam boiler, a forced-draft furnace having adraft fan, an electric motor for actuating it, and a movable motor-speedvarying device, included in the motor circuit, of a pressure-responsivedevice connected with said boiler, and an engine comprising a cylinder,a piston therein loaded to tend normally to move to one end of saidcylinder and operatively connected with said speed-controlling cylinder,valve means normally closing said end of said cylinder movable to openeither said pressure or relief connections, a valvemoving lever, anelectro-magnet on said lever, an armature on said valve means to besubstantially rigidified with said lever when the magnet is energized,said magnet being CURTIS L. HOWSE.

art, pressure j and relief connections for sa1d end of sa1d

